EP1830041B1 - Exhaust purification apparatus - Google Patents

Exhaust purification apparatus Download PDF

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Publication number
EP1830041B1
EP1830041B1 EP05807040A EP05807040A EP1830041B1 EP 1830041 B1 EP1830041 B1 EP 1830041B1 EP 05807040 A EP05807040 A EP 05807040A EP 05807040 A EP05807040 A EP 05807040A EP 1830041 B1 EP1830041 B1 EP 1830041B1
Authority
EP
European Patent Office
Prior art keywords
ammonia
vessel
urea water
exhaust
gas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
EP05807040A
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German (de)
English (en)
French (fr)
Other versions
EP1830041A4 (en
EP1830041A1 (en
Inventor
Shinya Sato
Takatoshi Furukawa
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hino Motors Ltd
Original Assignee
Hino Motors Ltd
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Filing date
Publication date
Application filed by Hino Motors Ltd filed Critical Hino Motors Ltd
Publication of EP1830041A1 publication Critical patent/EP1830041A1/en
Publication of EP1830041A4 publication Critical patent/EP1830041A4/en
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Publication of EP1830041B1 publication Critical patent/EP1830041B1/en
Expired - Fee Related legal-status Critical Current
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00—Ammonia; Compounds thereof
    • C01C1/02—Preparation, purification or separation of ammonia
    • C01C1/08—Preparation of ammonia from nitrogenous organic substances
    • C01C1/086—Preparation of ammonia from nitrogenous organic substances from urea
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/9404—Removing only nitrogen compounds
    • B01D53/9409—Nitrogen oxides
    • B01D53/9431—Processes characterised by a specific device
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/36—Arrangements for supply of additional fuel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B01D2251/2062—Ammonia
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/20—Reductants
    • B01D2251/206—Ammonium compounds
    • B01D2251/2067—Urea
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2259/00—Type of treatment
    • B01D2259/12—Methods and means for introducing reactants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2259/00—Type of treatment
    • B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
    • B01D2259/818—Employing electrical discharges or the generation of a plasma
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00002—Chemical plants
    • B01J2219/00004—Scale aspects
    • B01J2219/00006—Large-scale industrial plants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0894—Processes carried out in the presence of a plasma
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
    • F01N2240/25—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being an ammonia generator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2240/00—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being
    • F01N2240/28—Combination or association of two or more different exhaust treating devices, or of at least one such device with an auxiliary device, not covered by indexing codes F01N2230/00 or F01N2250/00, one of the devices being a plasma reactor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/06—Adding substances to exhaust gases the substance being in the gaseous form
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/14—Arrangements for the supply of substances, e.g. conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to an exhaust emission control device applied to an engine such as diesel engine.
  • some diesel engines have been provided with selective reduction catalyst incorporated in an exhaust pipe through which exhaust gas flows, said catalyst having a characteristic of selectively reacting NO x with a reducing agent even in the presence of oxygen.
  • a required amount of reducing agent is added upstream of the selective reduction catalyst and is reacted with NO x (nitrogen oxides) in exhaust gas on the catalyst to thereby reduce a concentration of the discharged NO x .
  • the urea water when added to the exhaust gas upstream of the selective reduction catalyst, the urea water is pyrolytically decomposed by heat of the exhaust gas into ammonia and carbon dioxide according to the following equation, and NO x in the exhaust gas on the catalyst is satisfactorily reduced and purified by the ammonia generated.
  • the invention was made in view of the above and has its object to provide an exhaust emission control device which can obtain satisfactory NO x reduction effect even at exhaust temperature lower than that required conventionally therefor and even in a vehicle with travel pattern of continuing operational status with low exhaust temperature, which can effectively generate ammonia from urea water and which can enhance controllability in adding ammonia to the exhaust gas.
  • the invention is directed to an exhaust emission control device with selective reduction catalyst incorporated in an exhaust pipe, ammonia being added upstream of the catalyst so as to reduce and purify NO x , said exhaust emission control device comprising an ammonia generator with a vessel for holding urea water and with an electrode for generation of ammonia through action of plasma on the urea water in the vessel, the ammonia generated in the ammonia generator being fed upstream of the catalyst.
  • the ammonia generated through action of the plasma on the urea water in the ammonia generator is fed upstream of the selective reduction catalyst, so that a required amount of ammonia can be surely added to the exhaust gas even in an operational status with low exhaust temperature to thereby be effectively reacted with NO x in the exhaust gas on the selective reduction catalyst; as a result, NO x in the exhaust gas is satisfactorily reduced and purified even at exhaust temperature lower than that required conventionally therefor.
  • Generation of ammonia can be easily and rapidly adjusted since the ammonia is generated through action of plasma on the urea water; and response in feeding the ammonia can be enhanced since the generated ammonia is added to the exhaust gas.
  • dielectric pellets are charged in the urea water in the vessel. Such charging of the dielectric pellets in the urea water brings about generation of plasma on surfaces of the pellets, thereby further effectively enhancing the action of generating ammonia from the urea water.
  • ammonia gas may be taken out from the ammonia generator. Addition of such ammonia gas to the exhaust gas causes no trouble of lowering the exhaust temperature, so that NO x reduction effect of the selective reduction catalyst in an operational status with low exhaust temperature can be further enhanced.
  • ammonia water may be taken out from the ammonia generator. Addition of such ammonia water to the exhaust gas substantially causes no trouble of lowering the exhaust temperature, though subtle heat may be taken upon evaporation of the water. Thus, NO x reduction effect of the selective reduction catalyst in an operational status with low exhaust temperature can be highly maintained.
  • a pH meter may be arranged which detects concentration of ammonia taken out from the vessel and a controller may be arranged which outputs a command on amount of ammonia to be fed upstream of the selective reduction catalyst on the basis of detected value from the pH meter, whereby actual amount of ammonia to be fed to the exhaust gas can be controlled with high response.
  • the above-mentioned exhaust emission control device of the invention has effects and advantages.
  • Ammonia is effectively generated through action of plasma on urea water in an ammonia generator and is fed upstream of the selective reduction catalyst so that, unlike the conventional supply of urea water, a required amount of ammonia can be surely added to exhaust gas without lowering in temperature of the exhaust gas; thus, even in an operational status with low exhaust temperature, NO x can be effectively reduced by the selective reduction catalyst. Because of ammonia being generated through action of the plasma on the urea water, the generation of the ammonia can be easily and rapidly adjusted; because of the generated ammonia being added to the exhaust gas, response in feeding the ammonia to the exhaust gas can be enhanced.
  • Fig. 1 is a schematic overall diagram showing an exhaust pipe pathway of an engine to which an exhaust emission control device of the invention is applied.
  • reference numeral 1 designates an engine such as diesel engine, the engine 1 illustrated having a turbocharger 2 with a compressor 2a to which air 4 from an air cleaner 3 is fed through an intake pipe 5.
  • the air 4 thus pressurized in the compressor 2a is further fed to an intercooler 6 where it is cooled.
  • the cooled air 4 from the intercooler 6 is guided to an intake manifold (not shown) from which it is guided to respective cylinders of the engine 1.
  • Exhaust gas discharged from the respective cylinders of the engine 1 is fed via an exhaust manifold 8 to a turbine 2b of the turbocharger 2.
  • the exhaust gas 7 thus having driven the turbine 2b is discharged via an exhaust pipe 9 to outside of the vehicle.
  • the selective reduction catalyst 10 is in the form of a flow-through type honeycomb structure and has a feature capable of selectively reacting NO x with ammonia even in the presence of oxygen.
  • the exhaust pipe 9 is provided with a spray nozzle 14 upstream of the casing 11, said nozzle injecting ammonia 13 generated in an ammonia generator 12 to add the same to the exhaust gas 7.
  • Fig. 2 shows an embodiment in which ammonia gas 13a is taken out from the ammonia generator 12 of Fig. 1 .
  • the ammonia generator 12 as ammonia 13, the ammonia gas 13a is generated and is fed to the exhaust gas 7 in the exhaust pipe 9.
  • reference numeral 15 denotes a vessel made from heat-resisting and insulating material such as polyethylene fluoride (e.g., Teflon (registered trademark)).
  • an electrode 16 Arranged centrally in the vessel 15 is an electrode 16 with its lower end extending adjacent to a bottom of the vessel 15 and with its upper end projected out of and fixed to the vessel 15.
  • the vessel 15 is encased by a casing 17 made from electro-conductive material such as iron, the casing 17 being connected to an earth 18.
  • wirework 19 made of stainless steel into which charged are dielectric pellets 19a which in turn may be made from material with high dielectric constant such as titania, barium titanate or alumina.
  • the wirework 19 is connected to the earth 18.
  • a urea water feed pipe 20 Inserted into and opened in the vessel 15 adjacent to the bottom thereof is a lower end of a urea water feed pipe 20 which serves to feed urea water 23a in a urea water tank 23 arranged above the vessel 15 into the vessel 15 via a urea water feed valve 21.
  • the electrode 16 is connected with power wire 25 which in turn is connected to a power source 24 such as battery.
  • the power wire 25 is provided with a controller 26 for control of voltage, driving pulse and the like.
  • an ammonia feed pipe 28 Opened to space 27 in the vessel 15 and above a liquid level of the urea water 23a is an ammonia feed pipe 28 which is connected via a pump 29 and an ammonia feed valve 30 to the spray nozzle 14.
  • the ammonia gas 13a generated in the space 27 of the vessel 15 is taken out through the ammonia feed pipe 28 and fed to the spray nozzle 14.
  • the ammonia feed pipe 28 is preferably provided with an ammonia gas storage tank 31 for temporary storage of the ammonia gas 13a generated in the space 27.
  • reference numeral 32 denotes a controller into which inputted is a liquid level signal 34 from a liquid-level meter 33 arranged in the vessel 15 for detection of a liquid level.
  • the controller 32 outputs a urea water feed command 35 to control an opening degree of the urea water feed valve 21 so as to keep constant an amount of urea water 23a in the vessel 15.
  • the controller 32 outputs an electricity control command 36 to control the controller 26 such that the electricity fed to the electrode 16 has predetermined voltage and drive pulse.
  • a detected pH value 38 from a pH meter 37 which detects pH of the urea water 23a in the vessel 15 (pH adjacent to the liquid level of the urea water 23a).
  • the controller 32 outputs ammonia feed command 39 to control an opening degree of the ammonia feed valve 30 to control the flow rate of the ammonia gas 13a fed to the spray nozzle 14.
  • controller 32 and an engine control computer exchange data such as revolution speed and load of the engine 1, detected temperatures of inlet and outlet temperature sensors 42a and 42b for the selective reduction catalyst 10 and intake air amount; on the basis of a current operational status judged from such data, an amount of NO x generated is presumed.
  • An amount of the ammonia gas 13a to match the presumed generation amount of NO x is calculated so that the required amount of ammonia gas 13a is added to the exhaust gas 7.
  • urea water 23a As shown in Fig. 2 , with a predetermined amount of urea water 23a being fed to the vessel 15 in the ammonia generator 12, electricity is fed from the power source 24 (battery) for control of voltage, driving pulse and the like by the controller 26 to a predetermined condition. Then, plasma is generated between the electrode 16 and casing 17 and, by the action of the plasma generated, the urea water 23a is decomposed as shown by (NH 2 ) 2 CO + H 2 O ⁇ 2NH 3 + CO 2 into ammonia and carbon dioxide. As a result, the urea water 23a in the vessel 15 is changed into ammonia water while the ammonia gas 13a is generated in the upper space 27 of the vessel 15, the ammonia gas 13a containing carbon dioxide and evaporated water.
  • the plasma acts on the urea water 23a for decomposition into ammonia gas 13a, so that the ammonia gas 13a can be generated easily and quickly.
  • the dielectric pellets 19a made of material with high dielectric constant such as titania, barium titanate or alumina are charged in the urea water 23a in the vessel 15, plasma is generated on respective surfaces of the pellets 19a, which substantially enhance decomposition reaction of the urea water 23a, resulting in effective generation of the ammonia gas 13a.
  • the ammonia generators 12 being arranged as shown in Fig. 3 , the ammonia gas 13a can be generated concurrently in large quantity for supply.
  • the controller 32 and the engine control computer exchange data such as revolution speed and load of the engine 1, detected temperatures by the inlet and outlet temperature sensors 42a and 42b for the selective reduction catalyst 10 and intake air amount to thereby detect the current operational status, so that a generation amount of NO x is presumed on the basis of the detected operational status.
  • An amount of the ammonia gas 13a to match the presumed generation amount of NO x is calculated and the ammonia feed valve 30 is controlled by the ammonia feed command 39 so as to feed the required amount of ammonia gas 13a.
  • the controller 32 can calculate ammonia concentration depending upon the detected pH value 38 of the pH meter 37 to compensate, on the basis of such ammonia concentration, the ammonia feed command 39 for control of the opening degree of the ammonia feed valve 30.
  • the urea water feed valve 21 is controlled by the controller 32 on the basis of the liquid level signal 34 from the liquid level meter 33 so as to feed, to the vessel 15, the urea water 23a adjusted to a predetermined concentration in the tank 23, whereby the amount of the urea water 23a in the vessel 15 is kept constant.
  • the ammonia generator 12 irrespective of the temperature of the exhaust gas 7, the ammonia generator 12 generates the ammonia gas 13a by the action of the plasma, the ammonia gas 13a being injected into and fed to the exhaust gas 7 in the exhaust pipe 9.
  • a required amount of ammonia can be surely added to the exhaust gas 7 even if the temperature of the exhaust gas 7 is low; thus, even in a vehicle with travel pattern of continuing the operational status with low exhaust temperature, a sufficient NO x reduction effect can be exhibited even at exhaust temperature lower than that conventionally required therefor. Since the ammonia gas 13a causes no problem of lowering the exhaust temperature upon addition to the exhaust gas 7, NO x reduction effect can be further highly maintained in the operational status with low exhaust temperature.
  • ammonia gas 13a Since the ammonia gas 13a is generated through the action of the plasma on the urea water 23a, the generation of the ammonia gas 13a can be easily and rapidly adjusted. Since the generated ammonia gas 13a is added to the exhaust gas 7, the amount of ammonia gas 13a to be fed to the exhaust gas 7 can be controlled with high response.
  • Fig. 4 shows an embodiment where ammonia water 13b generated through action of plasma on the urea water 23a in the vessel 15 in the ammonia generator 12 of Fig. 2 is injected upstream of the selective reduction catalyst 10.
  • the ammonia feed pipe 28 is opened in the liquid adjacent to the liquid level within the vessel 15.
  • the urea water 23a fed by the urea water feed pipe 20 to a position adjacent to the bottom of the vessel 15 flows upward while decomposed into ammonia and carbon dioxide through the plasma formed between the electrode 16 and casing 17.
  • the ammonia generated by decomposition dissolves in water so that ammonia water 13b exists in and especially at the upper part of the liquid in the vessel 15.
  • such ammonia water 13b is injected by the spray nozzle 14 through the pump 29 and ammonia feed valve 30 into the exhaust pipe 9 upstream of the selective reduction catalyst 10 for mixture with the exhaust gas 7.
  • Fig. 5 is a schematic diagram showing an embodiment to take out ammonia gas 13a from an ammonia generator 12 which is structurally different from that of Fig. 2 .
  • This ammonia generator 12 is provided with a laterally elongated vessel 40 made from heat-resisting and insulating material for holding urea water 23a.
  • a plurality of electrodes 16 are arranged in laterally spaced-apart relationship and are spaced at their lower ends to the liquid level of the urea water 23a by a predetermined distance.
  • the respective electrodes 16 are connected to power wire 25 which in turn is connected via a controller 26 to a power source 24 such as battery.
  • a power source 24 such as battery
  • Arranged on a bottom of the vessel 40 is an electrode plate 41 which is made from conductive material and is connected to the earth 18.
  • the vessel 40 is further provided with a urea water feed pipe 20 similar to that in the above-mentioned embodiment.
  • ammonia feed pipe 28 Further arranged in space 27 within the vessel 40 above the liquid level of the urea water 23a is an ammonia feed pipe 28 similar to that in Fig. 2 embodiment.
  • the ammonia feed pipe 28 is connected to the spray nozzle 14 via a pump 29 and the ammonia feed valve 30 of Fig. 2 .
  • Fig. 5 only the urea water 23a is fed in the vessel 40; however, alternatively, just like Figs. 2 and 4 , dielectric pellets 19 made from material with high dielectric constant such as titania, barium titanate or alumina may be charged in the vessel 40 in addition to the urea water 23a.
  • dielectric pellets 19 made from material with high dielectric constant such as titania, barium titanate or alumina may be charged in the vessel 40 in addition to the urea water 23a.
  • the urea water 23a is decomposed into ammonia and carbon dioxide, ammonia gas 13a being generated in the upper space 27 of the vessel 15.
  • the ammonia gas 13a can be generated by the action of the plasma.
  • the ammonia gas 13a is reacted with NO x to reduce NO x ; thus, even in a vehicle with travel pattern of continuing operational status with low exhaust temperature for a long time, a satisfactory NO x reduction effect can be obtained with exhaust temperature lower than that conventionally required therefor.
  • Fig. 6 is a diagram showing an embodiment to take out ammonia water 13b from the ammonia generator of Fig. 5 .
  • an ammonia feed pipe 28 is opened in the ammonia water 13b within the vessel 40.
  • urea water 23a fed to a position adjacent to the bottom of the vessel 40 by a urea water feed pipe 20 flows upward while gradually decomposed into ammonia and carbon dioxide by the plasma formed between electrodes 16 and an electrode plate 41, so that ammonia water 13b exits above within the vessel 40.
  • ammonia water 13b adjacent to the liquid level is injected upstream of the selective reduction catalyst 10 via a pump 29 and the ammonia feed valve 30 of Fig. 2 .
  • An exhaust emission control device of the invention can be effectively utilized in effectively generating ammonia from urea water and in enhancing controllability in ammonia addition for obtaining a satisfactory NO x reduction effect even in a vehicle with travel pattern of continuing operational status with exhaust temperature lower than that required conventionally therefor.
EP05807040A 2004-11-18 2005-11-17 Exhaust purification apparatus Expired - Fee Related EP1830041B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2004334578A JP4681284B2 (ja) 2004-11-18 2004-11-18 排気浄化装置
PCT/JP2005/021108 WO2006054632A1 (ja) 2004-11-18 2005-11-17 排気浄化装置

Publications (3)

Publication Number Publication Date
EP1830041A1 EP1830041A1 (en) 2007-09-05
EP1830041A4 EP1830041A4 (en) 2008-01-23
EP1830041B1 true EP1830041B1 (en) 2009-03-11

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ID=36407170

Family Applications (1)

Application Number Title Priority Date Filing Date
EP05807040A Expired - Fee Related EP1830041B1 (en) 2004-11-18 2005-11-17 Exhaust purification apparatus

Country Status (5)

Country Link
US (1) US20090145114A1 (ja)
EP (1) EP1830041B1 (ja)
JP (1) JP4681284B2 (ja)
DE (1) DE602005013285D1 (ja)
WO (1) WO2006054632A1 (ja)

Families Citing this family (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007321680A (ja) * 2006-06-01 2007-12-13 Toyohashi Univ Of Technology プラズマアシスト型尿素改質装置
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EP1830041A1 (en) 2007-09-05
JP4681284B2 (ja) 2011-05-11
WO2006054632A1 (ja) 2006-05-26
DE602005013285D1 (de) 2009-04-23
US20090145114A1 (en) 2009-06-11
JP2006144631A (ja) 2006-06-08

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